Re: [RFC 2/8] x86/acpi: Warn about multiple HPET tables

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 05/11/13 10:58, Jan Beulich wrote:
>>>> On 04.11.13 at 19:54, Andrew Cooper <andrew.cooper3@citrix.com> wrote:
>> --- a/xen/arch/x86/acpi/boot.c
>> +++ b/xen/arch/x86/acpi/boot.c
>> @@ -289,6 +289,17 @@ static int __init acpi_parse_hpet(struct acpi_table_header *table)
>>  		return -1;
>>  	}
>>  
>> +	/*
>> +	 * Some BIOSes provide multiple HPET tables. Warn that we will ignore
>> +	 * them.
>> +	 */
>> +	if ( hpet_address )
>> +	{
>> +		printk(KERN_WARNING PREFIX
>> +		       "Found multiple HPET tables. Only using first\n");
>> +		return -1;
>> +	}
> If there really are examples of this, and if those HPETs work
> properly, perhaps we should rather make use of them?
>
> Jan
>

The cause of this was two HPET acpi tables appearing.  This got 'fixed'
by a BIOS update (after which there was only a single HPET table), but I
felt it was worth warning about.

It might be nice to support multiple hpets is such a system existed.  It
would however be another fairly large chunk of work and I do not believe
I have appropriate hardware to test any development work on.

~Andrew